1. Field of the Invention
The present invention relates to a pump, especially to a pump installed with at least a check ring, wherein the check ring is capable of enclosing a main shaft for providing a liquid checking effect or capable of releasing the main shaft for forming a slit. Furthermore, the present invention provides a check ring used in a pump.
2. Description of Related Art
A pump is device for transporting liquid, air or special fluid medium, i.e. a machinery acting on fluid. Take a semiconductor wafer manufacturing factory for example, when a wafer is desired to be processed with cleaning and etching, a strong acid or string alkaline liquid is required, and during the process of a conventional kinetic pump being used for transporting the strong acid or strong alkaline liquid, the securing position of the impeller of the kinetic pump may have damages such as cavitation or acid corrosion thereby causing the liquid to be contaminated. As such, skilled people in the art have developed a pneumatic dual-diaphragm pump integrally made of an acid and alkaline resistant material, e.g. polytetrafluoroethylene (PTFE), which is trademarked as Teflon, thereby preventing the pump from being damaged by the strong acid or strong alkaline liquid.
The mentioned pneumatic dual-diaphragm pump is a volume pump, in which a pump body is connected with a pressure control valve, the pneumatic dual-diaphragm pump is to utilize the pressure control valve to drive a reciprocally-moving main shaft installed in the pump body, and the main shaft is received in a shaft hole, and two ends of the main shaft are respectively installed with a full-cover diaphragm, each diaphragm divides two pump chambers into an individual air chamber and an individual liquid chamber. When high pressure air is introduced into the pump, the pressure control valve is driven to act for allowing the main shaft to reciprocally move, thereby causing the two diaphragms to be deformed at the same time for changing the volume of each liquid chamber, so the liquid is sucked in or pumped out due to the pressure difference.
For providing a sealing effect to the pump chambers at two ends of the main shaft, a seal ring is respectively installed at two sides of the shaft hole, the main shaft is sleeved with the two seal rings and reciprocally moved. Wherein, the main shaft and the seal rings are made of an acid and alkaline resistant material, e.g. Teflon. When the liquid transportation is finished and the air source is not yet closed, the pressure control valve still drives the main shaft in the pump body to reciprocally move, so the main shaft is forced to directly and repeatedly rub against the seal rings without the heat dissipating and lubricating effects provided by the liquid, thereby causing the two components being heated and expanded due to heat, thus dead latch is formed. At this moment, if no proper action is taken, the main shaft and the seal rings may be melted due to the high temperature, thereby damaging the main shaft and the seal ring.